1. Field of the Invention
The invention generally relates to aircraft instrumentation and more particularly to an integrated attitude, altitude, and horizontal situation indicator display particularly suited for use in providing an aircraft pilot with critical inflight attitude, altitude, and horizontal situation information relative to a selected flight path in a more intuitively understandable manner. Furthermore, by combining on a single display intelligence, previously available only on multiple displays, a pilot is provided with all of the necessary flight parameters needed to control his flight path during both enroute navigation and final approach to landing under instrument conditions. This eliminates the heretofore existing need to scan several instruments in order to obtain the same information.
It is important to understand that the display unit of the instant invention is intended to operate in either a SITUATION MODE or a COMMAND MODE. In the SITUATION MODE the "true" angular relationships and offsets relative to a selected radial from a navigational facility, such as VOR, MLS, or ILS, or course, are displayed in a "true" pictorial form along with attitude and altitude information. The SITUATION MODE also embodies a heading submode in which errors from a selected heading are pictorially presented in an intuitively simple manner.
In the COMMAND MODE, angular relationships and offsets from a "computer-generated" course are displayed to a pilot in substantially the same manner as that heretofore described. The difference between the SITUATION MODE and the COMMAND MODE exists in the fact that in the SITUATION MODE, the pilot sees his true relation to a selected VOR, MLS, or ILS course or radial, and seeing this, can decide on the most appropriate flight path necessary to intercept and capture such course or radial. In the COMMAND MODE, however, a course is generated within a flight director computer and the pilot then sees his angular relationships and/or offsets with respect to the computer generated course which, if followed, will cause the aircraft to turn, climb, or descend as is necessary to smoothly intercept the selected VOR, MLS, or ILS course or radial.
Within the SITUATION MODE of operation for the display, submodes of heading (HDG), navigation (NAV), and approach (APPROACH) are available for displaying the total amount of intelligence necessary to control the aircraft. In the COMMAND MODE of operation, submodes of NAV and APPROACH are available to furnish all of the necessary information to control an aircraft to conform that the computer-generated flight path will carry the aircraft to its intended destination.
2. Description of the Prior Art
The prior art is, of course, replete with instrumentation including devices and systems the primary purpose of which is to provide pilots of aircraft with information relative to aircraft heading, altitude, attitude, course and glideslope deviation, as well as other information not here pertinent. Of primary concern here, however, is instrumentation having a capability for depicting altitude and attitude information, angular and lateral displacement from selected radials, and flight director computer steering information.
Horizontal situation indicators for providing heading errors and lateral offsets from VOR, MLS, or ILS radials are commercially available from many sources such as, for example, Sperry Rand Flight Systems Division, Phoenix, Ariz., King Radio Corporation, Olathe, Kans., Bendix Avionics Divisions, New York, N.Y., Lear Siegler Instrument Division, Grand Rapids, Mich., Collins Radio Company, Cedar Rapids, Iowa, and others.
Moreover, separate horizontal situation indicators are widely used in aviation and instrumentation capable of providing horizontal situation information only are manufactured and sold by most of the companies aforementioned. Typical of these displays are the Sperry RD-350A display, the Edo-Aire Mitchell Navigation Situation Display, the King Radio KCS 55 Pictorial Navigation System, and the Bendix FCS-810 Horizontal Situation Indicator. All of these instruments provide horizontal situation information, and only horizontal situation information.
Also well known are flight director indicators which serve to combine aircraft attitude displays with steering information or lateral and vertical offset information. Such instruments generally superimpose course and glideslope deviation needles, steering dots, or command bars over the face of a command gyroscopic display. Typical of these instruments are the Lear Siegler Mode 4058F and 4061D Attitude Direction Indicators, the Edo-Aire Mitchell Steering Horizon, the Sperry Flight Systems HZ-6F Flight Director, and numerous others.
Separate course and glideslope indicating systems are also manufactured by most of the aforenamed companies. These units generally are considered similar in design and function and are typically represented by the King Radio Company KI 213, KI 214, and KI 520 VOR/LOC indicators.
Consequently, it can be appreciated that an aircraft may be equipped with instrumentation fed by signals derived from pressure altimeters, radar altimeters, navigation receivers, heading reference systems, and onboard computers which utilize flight data and navigational signals and drive devices capable of providing displays designed to indicate situation errors, steering commands, pitch and roll commands, and/or course and glideslope deviations necessary to control an aircraft over either a selected or computed flight path.
It also must be noted that numerous terminal guidance systems heretofore have evolved for generating guidance commands adopted to be displayed to a pilot so as to enable him to control his aircraft in such a manner that will optimize his interception of a selected course or glideslope. Most of these systems have either been implemented as hard-wired analog logic or digital computer algorithms which, upon receipt of flight and navigational information from onboard radios and flight sensors, output guidance commands that may be implemented using one or more types of flight director displays.
Notwithstanding the numerous guidance systems currently available it is well recognized that under stress and adverse conditions encountered by pilots or aircraft operators, it is quite easy for a pilot to become confused by factors which normally would not overtax a human mind under less stress. When overtaxed, pilots tend to exhibit a propensity to incorrectly interpret even the simplest intelligence and fail to act, or, conversely, tend to over react. In addition, when under stress, a pilot's ability to scan several instruments and assimilate the information contained on each into an optimum control response, often is seriously impaired. A common difficulty encountered under instrument flight conditions is that of maintaining a continual, fast, repetitive scan of all flight instruments from which critical altitude, heading, attitude, and horizontal situation information must be obtained. A further common difficulty is that of fixation with a single instrument whose indicated parameter may have excessively varied from that desired. This type of fixation frequently results in excessive variation in parameters displayed on the other instruments, because of the excessive concentration devoted to the correction of the first discovered or discrepant parameter.
Consequently, in view of the recognized inadequacies of the human mind when under stress, there exists continuous concern and an ongoing effort to provide systems, devices, and techniques which simplify interpretation of data presented to pilots in flight, whereby the pilots continuously are better equipped to cope with conditions which heretofore often led to the undesirable consequences of pilot error.
It is, therefore, the general purpose of the instant invention to provide for a single display on which all critical flight and navigational parameters are simultaneously displayed and to do so in a manner which is intuitively simple for the pilot to use and interpret and thus enhance pilot efficiency and safety.